This invention relates to a valve arrangement for an internal combustion engine and more particularly to an improved valve and porting arrangement for a multiple valve internal combustion engine.
It is well known that the volumetric efficiency and output of an internal combustion engine can be improved by employing plural valves for each combustion chamber of the engine. By utilizing more than two intake and/or exhaust valves, it is possible to obtain a greater valve area for a given surface area of the combustion chamber and also to increase engine operating speeds due to the reduced inertia of the individual valve train components. For this reason, it has been the practice to employ four valve per cylinder, cylinder head assemblies for high performance engines. Recently, it has been proposed to utilize an even greater number of valves such as five valves per cylinder. Such five valve arrangement may employ three intake valves and two exhaust valves. With the normal valve placement of engines of this type, the intake valves have been positioned so as to lie on substantially one side of a plane containing the axis of the cylinder bore while the exhaust valves lie on the other side of this plane. Although such an arrangement affords the opportunity of relatively uncomplicated valve actuation, it presents certain difficulties.
In connection with the use of plural valves per combustion chamber, the increase in effective valve size is accompanied by a very close placement of the individual valves one to the other. If the exhaust valves are disposed as aforenoted (on one side of the plane containing the cylinder bore axis), they will be positioned in close proximity to each other. This means that the individual valve seats and, specifically, the exhaust valve seats are very closely disposed and a very small bridging area extends between the individual valve seats. As a result, this bridging area can become highly heated and can cause many problems.
It is, therefore, a principal object of this invention to provide an improved valve and porting arrangement for an internal combustion engine.
It is a yet further object of this invention to provide a valve and porting arrangement for an internal combustion engine that permits the use of multiple valves while avoids undue heating of the exhaust valve area.
It is another object of this invention to provide an improved exhaust valve placement for a multiple valve engine wherein the exhaust valves are not positioned in close proximity to each other.